1. Field of the Invention
The present invention relates to a printing apparatus.
2. Description of the Related Art
In a thermal printer, when power is successively supplied to a heating resistance element of a certain thermal head, there is provided a power-off time, in which the power supply is stopped, between a power-on time in which power is supplied to the heating resistance element for printing one-line data and a power-on time in which power is supplied to the heating resistance element for printing succeeding one-line data. The power-off time is provided for the purpose of avoiding a trailing phenomenon, and further, attaining a longer life of the heating resistance element of the thermal head (see, for example, Japanese Patent Application Laid-open No. Hei 5-345437).
Conventionally, the power-off time in which the power supply is stopped is set so as not to shorten the life of the heating resistance element of the thermal head even when a voltage for supplying power to the thermal head (hereinafter, referred to as “power supply voltage”) is high. The power-off time in which the power supply is stopped is kept constant irrespective of the power supply voltage.
Therefore, when the power supply voltage is low, the power-off time is unnecessarily long even though a shorter power-off time suffices as compared to the case where the power supply voltage is high. Thus, there is a problem in that, when the voltage is low, it takes a longer period of time to print a predetermined number of lines (hereinafter, referred to as “overall printing time”).